The influence on abdominal adhesions and inflammation in rabbits after exposure to differently charged polypeptides

Background: Abdominal adhesions develop on da- maged peritoneal surfaces and constitute a significant health related problem. Previous animal studies have shown promising anti-adhesive effects when adminis- tering the polycation α-poly-L-lysine (αPL) and the polyanion poly-L-glutamate (PG) together. The ob- jective of the study was to examine the effect of these differently charged polypeptides when administered by spraying and to evaluate any possible effect on fibrinolysis, fibrosis and inflammation. Methods: Rab- bits were treated with PLPG after cecal abrasive surgery and analysis from peritoneal biopsies of ac- tive tPa/PAI-1 complex and from peritoneal fluid of IL-6 and active TGFb1 at day 0, 1, 4 and 10 were measured after surgery. Histological specimens were analyzed on day 10 regarding inflammation and fib- rosis. Peritoneal adhesions were evaluated by adhe- sion score. All values were compared to the control group (NaCl). Results: PLPG-treated rabbits had a significant diminished adhesion score on day 10 as compared to the control group (p < 0.005). Signifi- cantly reduced collagen depositions on the perito- neum were seen in the PLPG group when evaluating the histological specimens (p < 0.05). No significant differences between the experimental and control groups were seen in peritoneal fluid when analyzing for active protein levels. Conclusion: This is the first study to investigate the effect on key parameters in adhesion formation as well as the preventive effect of the PLPG complex on abdominal adhesions in rabbits and also the first study where administration by spraying the polypeptides was used. PLPG was non- toxic in this setting and without significant differences in adhesion formation parameters and a significant reduction in adhesions was observed. This was veri- fied both macroscopically and histologically.